Thinking serious of a rebuild for more power.

If you really want the best, which is what your 348 deserves, you will go with Mahle Motorsport pistons, which are over $200 each. You can go crazy with options (DLC coated piston pins for $50+ each). Connecting rods should be either Arrow, or Carrillo. Arrow can do a set in Titanium for you as well for over $1000 each (this will bring some 360 technology to your engine). Or find a good used set of 360 Titanium rods and make sure they are reconditioned.

You can use high quality forged pistons from just about anybody because the bores are steel, but they don't have the same skirt treatment that Mahle offers, nor are they the same metallurgy. Also be careful who you use, there are a million different "engine experts" who take shortcuts because most owners don't know what they are looking at. You can pm me for more advice.

To give you a heads up, if the quote is less than $20,000 then you may end up with shortcuts , inferior work, or lesser quality parts. That $20,000 minimum doesn't have any "Ferrari tax" added either.

 

Would be interesting to see your experience.

 

Agree, Mahle pistons.

Be a little careful on the con rods. Changing to lighter weight con rods (like titanium) should be accompanied with a rebalance of the crankshaft (throw weights).

You can probably find 25 HP in a modern valve job {3-angel, 5-angle, eliptical, parabolic} especially if the valve seats are cut with a single point tool (like on a Serdi machine).

Another 10 is availiable with compression with careful attention to cc-ing of the combustion chamber and tuning of the engine after you get it installed.

But to find 100 HP, you are going to have to set your goal on 8500-9000 RPM for peak HP. You will loose a lot of TQ down low to move the HP peak up to this RPM point. This will basically require titanium con rods--or to put it another way, Ti roda at 8500 RPMs will have a 10-15 HP advantage on steel rods at 8500 RPMs just because of the reduced reciprocating loads.

It is likely you will also have to port the intake and exhaust (and cc them for matching purposes.)

The RPM band you choose will determine the length of the header tubes--and as on increases the diameter of the header tubes, the required length increases to remain tuned at the same point. For a 400 HP motorat 8500 RPMs a 348/355/360 engine will want 42mm ID tubes (about 1+7/8" diameter) and about 29" long. 321 is ideal, 305 is acceptable if coated on the inside) You are going to want a 20mm long transition between the 37mm equivalent exhaust port diameter and the 42mm tubing (7 degrees included angle of the transition). Packaging this in the engine bay and not cooking anythinig will be an interesting challenge.

 

Sorry guys, this seems like a really fun project, but why not buy a 355 and mod it slightly? Might be quite a bit cheaper and offer more performance. Unless this is a "just because I want to" kind of project.

 

Easier and cheaper option is just get more air into the engine, change the camshafts and Motec.

 

I would find a shop that has either a Rottler or Sunnen CNC hone with automatic taper control and also a cylinder head shop that uses a Newen fixed turning valve & seat machine. If 1 shop has both of these pieces of equipment you can be sure they are dedicated to providing the best to their customers. I know a few if you'd like referrals.

 

On that note, why not put a 355 engine/trans in a 348? You get the 60-90hp jump at a significant savings to doing all that work to a 348 along with a sixth gear...Especially if you sell the 348 engine and trans.

It'd probably be cheapest to sell the 348, buy a 355 and trade your front and rear bumpers and lower door panels to someone with a 348 that wants it to look like a 355...

 

The latest newen machines are having some concentricity issues compared to Serdi like machines with fixed blade cutters. I do love that the newen machines basically allow you to design your own cut though. Very neat.

 

One word:

Turbo.

 

Buy some low comp forged pistons, some bigger injectors and bolt 2 small turbos on it. Get some mapping done and away you go. Or a small supercharger.

Honestly.